Simple Interest — Infer rate, then compute four times the rate: Ramesh invests 10% of Rs 10000 at simple interest. After 3 years, the amount is Rs 2500. Find 4 times the actual annual interest rate.

Introduction / Context:
This problem checks understanding of reconstructing the simple interest rate from principal, time, and final amount, then scaling that rate as requested. The linear nature of SI makes this direct.

Given Data / Assumptions:

• Principal P = 10% of Rs 10000 = Rs 1000
• Amount after 3 years A = Rs 2500
• Simple interest model

Concept / Approach:
SI = A - P = 2500 - 1000 = 1500. Rate r% satisfies SI = P * r * t ⇒ r = SI / (P * t). Then compute 4 * r as a percent figure.

Step-by-Step Solution:

Verification / Alternative check:

Why Other Options Are Wrong:

• 250%, 300%, 5000%, 600%: Incorrect multiples of the recovered 50% per annum rate.

Common Pitfalls:

• Mistaking 10% of 10000 as 100 rather than 1000.
• Confusing percent and decimal forms of r.

Final Answer:
200%.